“The Democrats are living in a bubble on illegal immigration. They don't quite understand how it's being viewed in Middle America,” Jennings added.

All 10 Democrats raised their hands during one of last week’s debates when asked by moderator Savannah Guthrie if their health care plans would cover people who are in the country illegally.

Polls show the American public is divided on the issue.

A CNN poll conducted after last week’s debates showed that only 38 percent of respondents said health insurance coverage provided by the government should be available to undocumented immigrants, while 59 percent said it should not be.

“If the president uses that as an avenue of attack, I think it would pose a danger to any Democratic presidential candidate who supports that idea,” said Brad Bannon, a Democratic strategist and opinion contributor to The Hill.

“It is a dangerous issue, and I think Democrats have to make it clear that they want an expansion of the health care system, but it doesn’t cover illegal immigrants,” he added.

Trump has already lunged.

“The Democrats want to treat the illegals with health care and other things better than they treat the citizens of our country,” Trump told reporters Monday.

The idea of giving health care to undocumented immigrants is a relatively new position for Democrats.

The Obama administration and congressional Democrats then holding majorities in the House and Senate explicitly excluded undocumented immigrants from participating in ObamaCare when it was written 10 years ago.

But now, as Democrats eye the next steps in health care reform, major candidates are vowing that their plans would include coverage for undocumented immigrants.

And voters there, who are already stressed about illegal immigration, do not want to pay for their health care too, Republican strategists say.

Millions of Americans still don’t have health insurance, even after the Affordable Care Act extended health care to 20 million people.

And some of the states with the highest rates of uninsured people, such as Florida, also voted for Trump in 2016.

Jennings predicted that Democrats were handing Trump a tool to hammer them with.

“I don't think the Democrats understand what an epic disaster they have unleashed on their own party,” Jennings said.

"You can’t go into the Pennsylvania, Michigan and Wisconsin countrysides, find people who voted for Trump that have maybe voted for Democrats in the past, and say, 'Here’s how we’re going to get you back: free health care for illegal immigrants.'"